Gas-conserving regulators include oxygen regulators, which are used to supply a patient with a regulated flow of oxygen. The oxygen is supplied by a source of compressed oxygen, such as from a supply tank, which has its pressure reduced to a low pressure for delivery to the patient. Typical oxygen regulators employ a back-pressure piston to supply a continuous flow of that low pressure oxygen to the patient. Much of that oxygen is wasted because it is not inhaled by the patient.
To reduce the amount of wasted oxygen, oxygen-conserving regulators have been developed which tend to limit the oxygen flow to periods of inhalation. One way of controlling the oxygen flow is by electronic means. In a typical electronic conserver, a solenoid valve controls the flow of oxygen to the patient. The solenoid valve can accurately open to provide the flow of oxygen to the patient when the patient inhales, and close between breaths. Typically, the solenoid valve requires large energy requirements so that a C or D sized battery powering the solenoid valve might last only one month.